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How to add new RTC Keywords

Accepted answer

Thanks, you pointed me in the right direction.
open "MyProjectName" project
Go to "Process Configuration" tab
Expand: Project Configuration > Configuration Data > Work Items > Enumerations
then select "Choose the Enumeration to edit"="Keyword List"
and there is where I see the current values, and I was able to add new values.
Comments

Ah OK,
That enumeration is not an out of the box thing - it must be a custom attribute that was created, either as part of some customisation your organisation did, or as part of the specific project template you used to create the project.
It was a lucky coincidence that I pointed you to it!

I wondered what was meant at all. Mark, please consider providing more details of what you are doing next time around.